Aliens looking to meet us would be intelligent enough to scream, not whisper

The hunt for aliens has mainly focused on detecting weak signals that could be hidden in a huge spectrum of cosmic noise. However, a recent study has suggested that if an advanced extraterrestrial was interested in reaching out, it would send a signal that is easily detectable. In fact, they would even target specific areas if they wished to be noticed. Benjamin Zuckerman, study author and an astrophysicist from the University of California, said, “Our principal assumption is that a purposely communicative technological civilisation will do its technological best to establish communication with other extraterrestrial technological intelligences (ETIs).” The reason why SETI, or Search for Extraterrestrial Intelligence, has focused on looking for weaker signals till now is that a civilisation with limited power would send signals in all directions. By the time any of them reach a habitable world, it would have weakened considerably.

These signals could land on any frequency, and there is no way to know which one is a promising candidate. So humans end up scouring only a tiny fraction of them. However, the researchers of the new study believe that any civilisation capable of interstellar communication would not waste its technology by transmitting everywhere. In fact, it would shoot a sharp signal like a laser using highly directional transmission systems.

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Wavelength of transmission matters more than the strength

The study further states that power isn't the problem in this case, but whether Earth lies within that beam area is what matters. A system drawing on the order of 60 megawatts could also generate a signal that strong, they argue. “The most uncertain factor in our communication with a nearby ETI will not be power starvation, but rather the wavelength of transmission; this may be radio, infrared, or optical,” Zuckerman said. This means that if an alien civilisation were to send a well-aimed transmission, it would easily show up in routine astronomical data.

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Changes needed in way we search for alien life

Zuckerman has even presented the right kind of candidates to focus on while checking for such signals. It has to come from a place where communicative civilisations might exist, which can only be on water worlds. So attention should be on planets in the habitable zones of their stars. Further, technological intelligence takes billions of years to emerge. In the case of Earth, it was 4.5 billion years. So the stars of such planets should be similar to our Sun in age and stability. Within a sphere of about 200 parsecs, roughly 500,000 such stars can be found. Only about 200,000 are old enough to host advanced life. The study shows that the way we search for alien life needs to change, and broader wavelength ranges across nearby Sun-like stars should be the focus.